The purpose for security screening of a human body is to detect concealed weapons, military or police equipment or imitations, explosives, knives, inflammables, and other items that are hazards to safety. Conventional imaging technology in a security screening system adopts X-ray as a radiation source, which may be harmful to the human body. Terahertz wave with small photon energy is relatively safe and reliable compared to X-ray, and is suitable for a high-resolution imaging of a concealed object because of the short wavelength.
However, high imaging speed and high imaging accuracy of terahertz imaging are difficult to be satisfied at the same time.